1. Field of the Invention
The present invention relates to a registration correction method that is applicable to image processing for matching visible ray images that are formed in visible ray band areas with invisible ray images that are formed in invisible ray band areas. The present invention also relates to a vegetation state display method for displaying a state of vegetation in a clear view, using the registration correction method applied to image processing.
2. Description of the Related Art
In recent years, images formed by CCD cameras have been widely analyzed in various technical fields, including evaluation of activity degrees of plants. Images taken at each band by a CCD camera has a deviation ranging from a few pixels to tens of pixels. If those images are simply placed on top of one another, the resultant image is blurred. Even if an analysis is conducted on the resultant image in such a state, preferable results cannot be expected.                To measure the deviations among the images and match the positions among the images, the following methods have been suggested and used.        
1) Shifting a predetermined image among images overlapping one another, while visually checking the combined image.
2) Determining a point that is supposed to be common among monochrome images taken at each band, and placing the images on top of one another according to the deviations obtained from the determined point.
However, the above methods 1) and 2) have the following problems.
These days, the method 2) is employed in digital analysis devices that are widely used in conjunction with personal computers, but handling the digital analysis devices requires certain skills in the image positioning operation. Furthermore, the image positioning operation is time-consuming, requiring several hours for each operation.
As for the method 1), there are mechanical or electronic analog devices that employ the method 1) for the image positioning operations. However, these analog devices are expensive, and using one of those devices is also troublesome, as all digital images need to be converted into analog data prior to each operation.
Also, states of vegetation have been examined through visible ray images and near-infrared images in recent years. However, areas that do not show any vegetation are displayed in a single color in the prior art. As a result, there is a further problem that images that show vegetation states are difficult to see clearly.